The electrophoretic display (also called the electronic paper or the electronic ink) is distinct from the conventional CRT (Cathode Ray Tube) or LCD (Liquid Crystal Display). In an electrophoretic display, a plurality of micro cups is arranged on a substrate, and each micro cup contains a colored dielectric solvent and charged pigment particles suspending in the colored dielectric solvent. Two electrodes are arranged outside the micro cup. When the two electrodes alter the electric potential drop in the outer rim of the micro cup, the charged pigment particles move toward the electrode charged oppositely. The movement of the charged pigment particles changes the colors presented on the electrophoretic display. For the technology of controlling the electrophoretic display, please refer to a R.O.C. patent publication No. 538263 disclosing an “Electrophoretic Display” and a R.O.C. patent publication No. 200832031 disclosing an “Electronic Paper Device and Method for Fabricating the Same”. The theories and architectures disclosed in the prior arts for controlling an electrophoretic display are essentially similar and all utilize the potential difference to alter the colors presented on the display. The prior arts had fully demonstrated the difference between the electrophoretic display and CRT/LCD. Therefore, it will not repeat herein.
Refer to FIG. 1 for a conventional driver circuit of an electrophoretic display. The conventional driver circuit comprises a memory unit 1, a display controller 2, and a voltage driving unit 3. The memory unit 1 receives and stores a gray-level matrix signal 5. The display controller 2 reads the gray-level matrix signal 5 from the memory unit 1 and generates a voltage-difference matrix signal, which controls the voltage driving unit 3 to provide a frame refreshing signal to drive an electrophoretic display 4. However, the movement of the charged pigment particles needs a given interval of time to complete. Further, even though a portion of pixels remain unchanged, a frame must be completely refreshed before the next frame begins to be refreshed. Thus, the refreshing frame rate may be decreased in facing continuous inputting of the gray-level matrix signals 5. For example, suppose it takes a refreshing time of 100 ms to alter the color of all the pixels of the electrophoretic display 4 from full white to full black (or from full black to full white); then, the refreshing time becomes 300 ms to complete inputting three separated gray-level matrix signals 5. When the electrophoretic display is used in a touchscreen, the problem of low frame rate is particularly obvious. For example, it is possible for a Chinese character having many strokes that the screen may have not yet presented the last several strokes when a user has written the complete Chinese character. Therefore, the conventional driver circuit needs improving to enhance the frame rate of the electrophoretic display.